Liquid lubricated, elastomeric bearings, such as those shown in U.S. Pat. No. 3,932,004, have particular applicability to marine applications. So used, the surrounding environment itself provides the lubricant.
Traditionally, liquid lubricated bearings have had a metallic support shell such as brass or stainless steel. Those materials, however, tend to be quite expensive and relatively heavy. Simply to replace brass with a less expensive metal, however, does not reduce the weight, and the various manufacturing and machining steps required to complete the product maintain a significantly high cost for such bearings. Attempts at using non-metallic bearing shells--which virtually eliminates galvanic erosion--have been similarly unsuccessful, because such shells are so easily damaged by the heat necessary to cure the bearing member in situ and also because of the difficulty in achieving an acceptable bond between the bearing member and the shell within which it is to be housed. More recent advances have given rise to bearings wherein the support shell is made from fiberglass reinforced rubber, hereinafter designated as FRR.
The FRR material by itself, however, has a relatively flexible, non-rigid outer surface which is mentally unacceptable to many would-be users. In order to overcome this problem of mental acceptability it has heretofore been attempted to house an FRR bearing within a metallic housing, but that arrangement unnecessarily compounds the cost for no real technical advantage.
Moreover the flexibility in the outer surface of an FRR bearing does make it somewhat difficult to insert such a bearing into a rigid housing of customary construction.
Finally, FRR bearings are commonly manufactured in transfer molds which not only effectively limits the size of the bearing shells that can be so made but is also a particularly costly process for making relatively large bearings.